This invention relates to temperature threshold detectors.
The monitoring of the temperatures in operating plant is commonly performed by having thermocouples in the plant which are wired to instruments in a control room or to processors. Generally, this is a very satisfactory system. However, where there are a large number of thermocouples it becomes necessary to provide structural components to support cables connecting with the thermocouples. Even this can be acceptable in a static environment but where movable elements have also to be provided cable supporting components can either create problems of operation or restrict design freedom. A further problem may also arise with wired thermocouples, namely that of providing infallible sealing glands where the wires pass through a sealed containment vessel.
Wired thermocouples for temperature threshold detection can create problems as above stated in locations, such as nuclear reactors, where access is not readily obtainable and in sealed containers for heat generating materials, such as in flasks for irradiated nuclear fuel.
The present invention seeks to solve the above stated problems by providing a simple form of unwired transmitting sensory, and a detector receiver. Whilst this does not wholly eliminate the use of wires (which are required at the detector) it allows wiring to be either located in a more acceptable position or for sealing glands to be avoided.